Answer: A. 1
Mangrove swamps are wetland ecosystem found in the coastal area. These are found in regions where water body and terrestrial land meets. These ecosystem are dominated by mangrove trees due to their ability to servive in harsh saline water conditions. The roots of mangrove trees exhibit salt filteration system. These trees are habitat of many bird and animal species. The roots of these trees provide shelter, to underwater aquatic plant and animal species such as algea, prawns, sponges and fishes. Mangroves trees and algea are primary producers of the food chain in mangrove ecosytem. Mangrove tree leaves are eaten up by herbivores insects and algal species are consumed by large number of sea animals. Hence, mangrove tree and algea will be on the 1 number of the food chain.